The current findings of research are limited by weak study design and non-standardized instruments which decrease the level of evidence.
Systematic reviews of efforts to increase utilization of adolescent health services in LMICs, reported that the evidence was often limited by weak study design [ 14, 15], such as lack of data on process evaluations, long-term follow-up, cost-effectiveness, scale-up, and the impact on health outcomes.
However, the distribution of the tones, heights and annotations of the bars (studies) populating this row of the matrix suggests that the evidence for such a gradient was mostly contributed by comparatively weak study designs, some of which found a gradient only in 'intermediate' rather than 'hard' outcome measures.
As a consequence, the matrices make it particularly clear that large parts of the available evidence base depend wholly or partly on weak study designs, as well as on 'intermediate' outcome measures represented by the grey bars.
However, many promising interventions have not been evaluated properly or were tested using weak study designs.
Taken into account the weak study designs, no strong conclusions can be drawn.
Of the studies that did not find an association, two had weak study designs, including one small cross-sectional study.
For instance, inconsistent MTBI definitions, weak study designs and pervasive biases were common problems throughout the literature.
Also impeding substantive advancements are a host of poorly designed and inadequately tested measures, which are often applied using very weak study designs.
Many are single case studies, some quite anecdotal, while others are biased or characterised by a weak study design.
